Electric incandescent lamps



Oct. 3, 1967 J. w. T. WRIGHT ELECTRIC INCANDESCENT LAMPS 2 Sheets-Sheet 1 Filed March 20, 1964 Oct. 3, 1967 J. w. T. WRIGHT 3,345,526

ELECTRIC INCANDESCENT LAMPS Filed March 20, 1964 2 Sheets-Sheet 2 United States Patent 3,345,526 ELECTRIC INCANDESCENT LAMPS John Willoughby Thomas Wright, Leicester, England, assignor to Associated Electrical Industries Limited, London, England, a British company Filed Mar. 20, 1964, Ser. No. 353,421 Claims priority, application Great Britain, Apr. 4, 1963, 13,426/63 5 Claims. (Cl. 313-42) This invention relates to electric incandescent lamps of the capless type. In such lamps the conventional metal cap secured to the envelope and by which the lamp is supported in a holder is omitted, and the envelope of the lamp includes an external pinch through which the leadin conductors to the filament extend to the exterior of the envelope to form terminals so that when the lamp is supported in a holder designed to receive the pinch, the external terminals engage with electrodes in the holder. Usually the lead-in conductors in the form of wires are returned into the pinch and the looped portion formed thereby bent back towards or against the outer surface of the pinch.

In miniature capless lamps where the length of the lead-in wires between the pinch and the filament is relatively short, it is usual to seal part of each lead-in wire in insulating relation in a glass bead to prevent relative movement between the wires. In larger lamps where the length of the lead-in wires is necessarily increased, deflection of the wires with relation to the flattened pinch may take place with consequent damage to the filament.

In accordance with the present invention, a capless electric incandescent lamp comprises a body of vitreous material rigidly supported within the lamp envelope by a vitreous exhaust tube projecting from a pinch which seals the envelope and provides a base for the lamp, and with each lead-in conductor to the or each filament of the lamp supported in insulating relation by said body and extending through said pinch to form an electrical terminal adjacent the outer surface of the pinch.

Since the vitreous body with the lead-in conductors supported thereby is in turn supported on the exhaust tube, it may form a convenient sub-assembly which can readily be handled prior to it being sealed Within the envelope of the lamp. After the lamp has been scaled the body is rigidly secured to the pinch and is spaced apart therefrom so reducing the length of the lead-in wires between the rigidly secured body and the filament.

In certain embodiments of the invention it may be desirable for the lamp to be provided with more than one filament, but in accordance with the invention the lead in wires for each filament extend through and are supported by the body.

The lead-in wires from the terminals of the lamp and the end of the wires remote from the filament may either be looped back into the pinch with the looped portion bent back towards or against the outer surface of the pinch, or have the end portion of the lead-in wires bent back against the pinch, but not looped back into the pinch. It is to be understood that if the lead-in wires are formed from material of fairly substantial thickness the resilience of the material may cause the wires to remain slightly spaced apart from the wall of the pinch and not be in contact with it.

According to a feature of the invention, the body of vitreous material may be in the form of a shaped end portion of a glass tube, the tube extending in over-lapped coaxial relation with the exhaust tube, and the tube may provide a flared portion which serves to deflect internal convection currents in the gas filling of the lamp away from the base of the lamp when the lamp is energised with the base uppermost.

3,345,526 Patented Oct. 3, 1967 In order that the invention may be more readily understood, it will now be described by way of example with reference to the accompanying drawings, in which:

FIGS. 1 and 2 are a front elevation and side elevation, respectively, of an incandescent lamp in accordance with one embodiment of the invention,

FIGS. 3 and 4 are a front elevation and side elevation, respectively, of a lamp in accordance with a second embodiment of the invention,

FIGS. 5 and 6 are a front elevation and side elevation of a lamp in accordance with a third embodiment of the invention, and

FIG. 7 is a side elevation of a lamp in accordance with a still further embodiment of the invention.

In all the figures, reference numeral 1 indicates the glass envelope of an electric incandescent lamp, the envelope being sealed by means of a glass pinch 2 of generally rectangular form which provides a base for the lamp. One or more filaments 3 are provided within the envelope and each filament is supported at each end by a lead-in conductor in the form of a wire 4 which extends through the sealed pinch 2 to the exterior of the envelope and forms a terminal 5 of the lamp. In the embodiments of the invention illustrated, the end of each lead-in wire is looped back into the pinch and the looped portion 6 is bent back against the outer surface of the pinch.

Referring particularly to FIGS. 1 and 2, an embodiment of the invention is illustrated in which two separate filaments are provided. Each lead-in wire is sealed through and supported by a body of vitreous material 7 which is in turn supported by the vitreous exhaust tube 8 of the lamp, the exhaust tube being sealed through the pinch. Prior to the sealing of the lamp the body 7, mounted on the exhaust tube and supporting the lead-in wires and the filament 3, forms a sub-assembly which can readily be handled, and on sealing the lamp the sub-assembly is positioned within the envelope, the base of which is flattened to produce the pinch 2 and at the same time rigidly support the body and the lead-in wires.

Referring to the second embodiment of the invention illustrated in FIGS. 3 and 4, the body takes the form of the shaped end portion 7 of a glass tube 9, the tube extending coaxial in overlapped relation with the exhaust tube, and the end of the tube remote from the portion 7' is sealed into the pinch 2. The remaining parts of the lamp are similar to those shown in FliGS. 1 and 2, and in both embodiments of the invention where two filaments are shown the four terminals 5 of the lamp are arranged in spaced apart relation two on each side of the flattened glass pinch.

The embodiment of the invention illustrated in FIGS. 5 and 6 employs a single filament of arcuate form which is supported at its ends by lead-in wires 4 and is supported intermediate the lead-in wines by support members 10. The lead-in wires 4- are supported by the flattened end portion of a glass tube 11, and the support members 10 are sealed into a stem extending from the flattened end portion of the tube. The tube 11 provides a flared portion 12 in the form of a skirt which serves to deflect internal convection curernts in the gas filling of the lamp away from the pinch 2 when the lamp is energised with the base uppermost. The flattened end of the tube 11 which provides the body is supported by the exhaust tube 8 and fuses 13 are positioned within the flared portion 12, one in series with each of the lead-in Wires 4'.

The embodiment of the invention illustrated in FIG. 7 is similar to that shown in FIGS. 5 and 6, except that the tube 11 is not provided with a flared portion 12, and that the end of the tube which is remote from the flattened end thereof extends into the pinch 2. Fuses 13, of which one is shown, are connected in series with the 3 lead-in wires of the lamp and are positioned within the tube 11.

In all the embodiments of the invention the body of vitreous material is supported by the exhaust tube and consequently it is essential that the exhaust tube is not blocked by the body, but that the exhaust tube is in open communication with the interior of the envelope through an opening 14 formed in the body. It is to be understood that the shape of the glass envelope may be of any convenient form, and is not limited to the shapes illustrated in the drawings. Furthermore, the end lead-in wires forming the terminals 5 of the lamp may be turned up in other positions to those shown, towards or against the outer surface of the pinch.

What I claim is:

1. An electric incandescent lamp comprising an envelope of vitreous material, a flattened pinch sealing said envelope, two filaments within the envelope, two lead-in conductors to each filament, an end portion of each of said lead-in conductors extending in sealed relation through said pinch to the exterior of the envelope and forming an electrical terminal adjacent the outer surface of said pinch, a vitreous exhaust tube projecting into said envelope from said pinch, a second vitreous tube arranged in overlapped coaxial relation with said exhaust tube, the free ends of said tubes in the envelope fused together to provide an enlarged head portion'projeoting outwardly of the exhaust tube with each of said lead-in conductors extending in spaced relation through said head portion.

2. An electric incandescent lamp as claimed in claim 1 in which the end of the second tube away from that having the enlarged head portion is sealed into said pinch.

3. An electric incandescent lamp as claimed in claim 1 in which said enlarged head portion includes a flared portion directed toward the pinch to deflect internal convection currents.

4. An electric incandescent lamp comprising an envelope of vitreous material, a flattened pinch sealing said envelope, a filament within the envelope, two lead-in conductors to the filament, an end portion of each of said lead-in conductors extending in sealed relation through said pinch to the exterior of the envelope and forming an electrical terminal adjacent the outer surface of said pinch, a vitreous exhaust tube projecting into said envelope from said pinch, a second vitreous tube arranged in overlapped coaxial relation with said exhaust tube having an enlarged head portion projecting outwardly thereof and supported by the end of the exhaust tube, said second vitreous tube having an opening therein registering with the opening in said exhaust tube, and each of said lead-in conductors extending through said head portion.

5. An electric incandescent lamp comprising an envelope of vitreous material, a flattened pinch sealing said envelope and providing a base for the lamp, at least one filament within the envelope, two lead-in conductors to each filament, an end portion of each of said lead-in conductors extending in sealed relation through said pinch to the exterior of the envelope, the end of each of said portions sealed into said pinch to provide a loop with each of said loops bent back between the outer surface of said pinch to form an electrical terminal, a first vitreous tube having one end sealed into the pinch and the other end located in the envelope, a second vitreous tube arranged in overlapped c'o-axial relation with said first tube with one end portion of said second tube sealed into said pinch and the other end having an enlarged head portion projecting outwardly thereof and supported by the end of the first tube, said second vitreous tube having an opening therein registering with the opening in said first tube, and each of said lead-in conductors extending through said head portion.

References Cited UNITED STATES PATENTS 1,650,602 11/1927 Burnap 313--43 2,021,758 11/1935 Van Horn 315-73 2,924,736 2/1960 Kotsch 31343 2,937,308 5/1960 Howles et a1. 313-315 3,250,939 5/1966 Dayton et al. 313-317 DAVID J. GALVIN, Primary Examiner. 

1. AN ELECTRICAL INCANDESCENT LAMP COMPRISING AN ENVELOPE OF VITREOUS MATERIAL, A FLATTENED PINCH SEALING SAID ENVELOPE, TWO FILAMENTS WITHIN THE ENVELOPE, TWO LEAD-IN CONDUCTORS TO EACH FILAMENTS, AN END PORTION OF EACH OF SAID LEAD-IN CONDUCTORS EXTENDING IN SEALED RELATION THROUGH SAID PINCH TO THE EXTERIOR OF THE ENVELOPE AND FORMING AN ELECTRICAL TERMINAL ADJACENT THE OUTER SURFACE OF SAID PINCH, A VITREOUS EXHAUST TUBE PROJECTING INTO SAID ENVELOPE FROM SAID PINCH, A SECOND VITREOUS TUBE ARRANGED IN OVERLAPPED COAXIAL RELATION WITH SAID EXHAUST TUBE, THE FREE ENDS OF SAID TUBES IN THE ENVELOPE FUSED TOGETHER TO PROVIDE AN ENLARGED HEAD PORTION PROJECTING OUTWARDLY OF THE EXHAUST TUBE WITH EACH OF SAID LEAD-IN CONDUCTORS EXTENDING IN SPACED RELATION THROUGH SAID HEAD PORTION. 